This wikiHow teaches you how to block calls from unknown numbers on your Android phone, as well as how to block all foreign calls to your device. Since most Android devices don't have a built-in call blocking feature, you need to use the "Should I Answer?" to block unknown incoming calls.
Step
Method 1 of 3: Blocking One Number

Step 1. Open the Phone app
This application icon looks like a handset and is usually displayed on the home screen.
If you are using a Samsung Galaxy device, move on to the next method

Step 2. Access the list of recent calls
The location of the options is different for each device. If the Phone app doesn't show a list of recent calls right away, look for an icon with a clock and the words "Recent".

Step 3. Touch and hold the number you want to block
After that, the menu will be displayed.

Step 4. Tap Block/report spam
The name of this option may be different, but you can usually see the line or text “ Block A confirmation message will be displayed.
You may need to select the option “ Blacklist " or " Block list ”.

Step 5. Touch Block when asked to confirm
You will no longer receive calls from that number.
Method 2 of 3: Block All Unknown Numbers on Samsung Galaxy

Step 1. Open the Phone app
The app with the phone icon is on the home screen. You can also swipe up or down the screen to open the page/app drawer and look for the icon.

Step 2. Touch
It's in the upper-right corner of the screen. Once touched, a drop-down menu will appear.

Step 3. Touch Settings
This option is in the drop-down menu. After that, the call settings page (“Call Settings”) will be opened.

Step 4. Touch Block numbers
This option is in the " CALL SETTINGS " section.

Step 5. Touch the white "Block anonymous calls" switch
The color of the switch will change indicating that the device will no longer receive calls from unknown numbers.
- If you only want to block one number, type the appropriate number into the " Add phone number " field at the top of the page and tap “ Done ' on the keyboard.
- You can still receive calls from people who are not in contacts, as long as they use an active phone number. If you want to restrict your device from receiving incoming calls only from people in your contacts list, use the "Should I Answer?" app.
Method 3 of 3: Block All Unknown Numbers on Android Device

Step 1. Download the "Should I Answer?
".
The app reviews incoming and outgoing calls and can be set to reject all unknown calls (including calls from numbers not stored on the device). To download it, go to
Google Play Store, then follow these steps:
- Touch the search bar.
- Type should I answer
-
Touch Should I Answer?
”
- Choose " INSTALL ”
- Touch " ACCEPT ”

Step 2. Open Should I Answer
Touch the button “ OPEN ” in the Google Play Store window or the Should I Answer? which looks like an octopus in the device's page/app drawer.

Step 3. Touch CONTINUE
It's at the bottom of the screen.

Step 4. Touch the SETTINGS tab
This tab is at the top of the screen.

Step 5. Scroll to the "Block INCOMING Calls from" section
This segment is in the middle of the “Settings” page.

Step 6. Enable incoming call blocker
Touch the white switch
next to some or all of the following options:
- ” local negative rated numbers ”
- ” community negative rated numbers ”
- ” numbers not stored in contacts ”
- ” hidden numbers ”
- ” foreign numbers ”

Step 7. Reject incoming messages if necessary
If you want to prevent unknown numbers or users from sending you messages, scroll to the "Block INCOMING SMS" section and tap the white toggle next to the options you want to apply.

Step 8. Close Should I Answer
Application settings will be saved. From now on, calls from unknown numbers will be blocked.